Technologies for Fixed Mobile Convergence (FMC) have been emerging in recent years, with the aim of providing a single phone for both fixed and mobile services, where the phone switches between networks ad hoc. Unlicensed Mobile Access (UMA) and the IP Multimedia Subsystem (IMS) are standards that support FMC. In this regard, reference is made to FIG. 1, which is a prior art illustration of a system having a mobile core network and devices that access the network, in conformance with the UMA standard.
Generally FMC technology uses “dual mode handsets”. Dual mode handsets are wireless phones that include both Wi-Fi radios, for local area access, and cellular radios, for wide area access. The Wi-Fi radio accesses wireless LANs in homes, offices and public hot spots, and the cellular radio accesses cellular networks. During a phone call, a dual mode handset monitors its location for the presence of Wi-Fi and cellular services, and selects the “better” access mode based on signal strength and other criteria. As a user moves between cellular and Wi-Fi coverage areas, the handset automatically switches between Wi-Fi and cellular access modes. A make-before-break handoff procedure ensures a seamless transition.